Azoniaanthracene dye developing agents in diffusion transfer



United States Patent Ofi ice 3,535,114 Patented Oct. 20, 1970 3,535,114 AZONIAANTHRACENE DYE DEVELOPING AGENTS IN DIFFUSION TRANSFER Paul H. Stewart, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Oct. 30, 1%7, Ser. No. 679,186

Int. Cl. G03c 5/54 US. Cl. 9629 17 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the art of photography, and more particularly, to multicolored dye diffusion transfer systems and to the dye developers employed therein.

Compounds which contain in the same molecule both the chromophoric system of a dye and a photographic silver halide developing moiety have been described in the photographic art as useful compounds in photographic elements for preparing color images by diffusion transfer processes. Such compounds are commonly called dye developers. Color diffusion transfer processes are disclosed in US. Pats. 3,146,102, 3,161,506, British Pat. 804,971, and French Pat. 1,313,767, as well as elsewhere in the literature.

Photographic elements containing such dye developers generally comprise a plurality of photosensitive silver halide emulsions wherein each of these emulsions is selectively sensitized to a different region of the spectrum. A dye developer is positioned contiguous to the silver halide in each of such emulsions, the dye developer being substantially complementary in color to the color of light recorded in the contiguous silver halide. Such a photoelement is processed with an alkaline composition. The latent image is developed in the negative image areas with the dye developers, this development immobilizing the dye developers in such negative image areas. The dye developers in the unexposed areas diffuse to the surface imagewise and are transferred to a reception layer or receiving sheet to form a positive multicolor image.

In the above-described dye developer diffusion transfer processes, the processing compositions or activators used to initiate development of the exposed light-sensitive elements are strongly alkaline and contain alkaline metal hydroxides, such as sodium hydroxide for imparting high alkalinity. The processing compositions are generally aqueous liquids or solutions and generally contain thickening agents such as hydroxyethyl cellulose. The development of the photosensitive element by treatment with the alkaline processing solution may be conducted in camera by providing the processing solution in a rupturable container or pod. Upon rupturing, the processing composition is released and spread uniformly across the picture area of one or more consecutively exposed images while in contact with the reception layer. Other suitable means such as spraying, dipping, roller coating, etc. may be employed to apply the processing solution to the exposed element and to initiate its development thus resulting in a positive image on the dye developer reception layer.

It is an object of this invention to provide a novel dye developer diffusion transfer process.

It is another object of this invention to provide novel dye developers characterized as being capable of forming both positive and negative images in color.

These and other objects of the invention are accomplished by providing a photographic element comprising a light-sensitive silver halide emulsion layer and, contiguous to the silver halide emulsion layer, a salt of dihydroxyazoniaanthracene as a novel dye developer.

It has been discovered that a photographic image in color can be formed by processing an exposed photographic element comprising a support, a light-sensitive silver halide emulsion layer and a dye developer contiguous to the silver halide of the silver halide emulsion layer, which dye developer comprises a salt of a dihydroxyazoniaanthracene. The photographic element is processed with an alkaline liquid and this causes the dye developer to transfer to a dye developer reception layer.

Surprisingly, it has been found that the novel dye developers of the present invention may not only be transferred to the receiving sheet to form a positive image in color, but may also be transferred to the receiving sheet to form a negative image in color.

According to one aspect of the invention, an exposed photographic element containing the novel dye developer is processed by contact with an alkaline processing solution to yield a light brown, positive transfer image. In accordance With this aspect of the invention, the dye developer is immobilized in regions of exposure of the silver halide emulsion layer, while the dye developer in the undeveloped regions diffuses imagewise, in register to the dye developer reception layer.

According to another aspect of the invention, an exposed photographic element which contains the hydroquinone form of the dye developer of the present may be processed with an' alkaline processing solution to produce a positive transfer image or may be processed in the presence of sodium sulfite to yield a blue, negative transfer image. In accordance with this aspect of the invention, a dye of a different hue may be formed and transferred in the regions of exposure of the silver halide emulsion layer, to the image receiving layer to form a negative image thereon, but will not diffuse from the undeveloped regions of the emulsion layer to the receiver.

The novel azoniaanthracene dye developers of the present invention may be generally represented by the following structural formulas and include hydroquinone derivatives of the formula:

I OH

and catechol derivatives of the formula:

OH I A1 3 Represenentative dye developers within the scope of the present invention include:

5,8-dihydroxy-4a-azoniaanthracene bromide; 5,6-dihydroxy-4a-azoniaanthracene bromide; 5,6-dihydroxy-8-phenyl-4a-azoniaanthracene bromide; 5,8-dihydroxy-4a-azoniaanthracene perchlorate;

5 ,6-dihydroxy-4a-azoniaanthracene perchlorate; 5,6-dihydroxy-8-phenyl-4a-azoniaanthracene perchlorate; 5,6-dihydroxy-8-methyl-4a-azoniaanthracene bromide;

5 ,8-dihydroxy-4a-azoniaanthracene chloride; 5,6-dihydroxy-4a-azoniaanthracene chloride; 5,6-dihydroxy-8-propyl-4a-azoniaanthracene bromide;

and the like.

The azoniaanthracene dye developers of the present invention may be suitably produced by the aromatic cyclodehydration of [1 azonia 2-(1,3-dioxolan-2-yl)benzyl] aromatic diesters, in the manner disclosed in US. patent application Ser. No. 368,979 to Fields et al., filed on May 20, 1964, now U.S. Pat. No. 3,375,253 and corresponding French Pat. 1,440,237, issued Apr. 18, 1966, the disclosure of which is hereby incorporated by reference. Thus, according to the method disclosed therein, 5,8-dihydroxy- 4a-azoniaanthracene bromide may be produced by reacting 2-[l-azonia-2-(1,3-dioxolan-2-yl)benzyl]hydroquinone diacetate and hydrogen bromide in acetic acid. Similarly, other novel dye developers may be produced by reacting an appropriate aromatic diester with a suitable cyclodehydrating agent, e.g., hydrochloric acid, sodium perchlorate, and the like.

The processing compositions or activators used to initiate development of the exposed light-sensitive elements in accordance with the invention are alkaline in nature. Such processing compositions may have a pH of about 11 or more. Alkali metal hydroxides, such as sodium hydroxide, and sodium carbonate, may be used in the processing composition for imparting the alkalinity. However, the preferred processing solution that may be employed in the process of the present invention comprises an aqueous solution of sodium metaborate octahydrate. The aqueous processing solutions may be suitably employed in rupturable pods for in-camera processing such as described in US. Pat. 2,435,717. It is desirable to include a thickening agent such as hydroxyethyl cellulose or carboxymethyl cellulose when the processing solution is to be employed in this manner. Thickened processing compositions typically have viscosities of at least 5,000 centipoises to 100,000 or even 200,000 centipoises.

The utilization of the aforesaid alkaline processing solutions for activation of the photosensitive element containing the azoniaanthracene dye developer results in the production of a light brown positive image being transferred to the dye developer reception element. As previously mentioned, a positive image is formed when the dye developer is immobilized in the regions of exposure of the silver halide emulsion layer thus permitting the dye developer in undeveloped regions to diffuse imagewise to the reception layer.

According to another aspect of the invention, a negative transfer image may be formed on the receiver sheet by processing the photosensitive element of the present invention in the presence of sodium sulfite. More particularly, exposed photosensitive elements that contain the above-described hydroquinone derivatives of the present azoniaanthracene dye developers, i.e.,

(B R /\\N I on may be processed with an alkaline processing solution in the presence of sodium sulfite and will yield a blue negative transfer image.

In the photographic elements useful in the invention, the novel dye developers are preferably incorporated in hydrophilic organic colloidal vehicles or carriers which comprise the layers of the photographic element dissolved in high-boiling or crystalloidal solvents and dispersed in finely divided droplets. Typical high-boiling, water-insoluble solvents that may be used to dissolve dye developers in preparing the dispersions of the invention are described on page 2, col. 2 and page 3, col. 1 of US. Pat. 2,322,027.

The dye developers may also be incorporated into vehicles soluble in organic solvents which are also solvents for the dye developers. Likewise, other incorporating techniques for the dye developers such as ball-milling may be utilized.

As previously mentioned, the dye developers are utilized contiguous to the silver halide of the photographic elements. The dye developers may be incorporated directly in the silver halide emulsions or preferably positioned in a sublayer contiguous to each silver halide emulsion layer. The contiguity of the dye developer with respect to the silver halide can take the form of a mixed packet system wherein the dye developer can be present in a matrix surrounding a particle or globule containing silver halide grains.

A wide variety of colorless hydroquinone derivatives may be utilized in the dye developer diffusion transfer systems of the invention and constitute auxiliary silver halide developing agents. Such colorless hydroquinone derivatives are substantially insoluble in water and diffusible in the hydrophilic organic colloids comprising the present photographic elements in the presence of the alkaline processing compositions. Typical suitable colorless hydroquinone derivatives are listed in columns 7 and 8 of U.S. Pat. 3,146,102 and are preferably employed in one or more layers of the light-sensitive element.

The auxiliary developers, such as 4-methylphenylhydroquinone, materially reduce the minimum image density and thus improve the quality of the print. The auxiliary developers may be suitable provided in any of the layers of the photosensitive element, in the processing liquid or in the reception element. Preferably, the auxiliary developer is provided as an overcoat of the photosensitive element. Ascorbic acid may likewise be suitably employed as an auxiliary developer in the dye diffusion transfer system of the present invention.

A wide variety of difiusible onium compounds may also be utilized in the systems of the present invention. Such onium compounds, that is, compounds that contain an organic cation, are diffusible in the hydrophilic organic colloids comprising the present photographic elements in the presence of the alkaline processing compositions. Suitable onium. compounds are typically quaternary ammonium compounds, quaternary phosphonium compounds or tertiary sulfonium compounds. A particularly useful class of onium compounds are heterocyclic quaternary ammonium compounds that are capable of forming diffusible methylene bases in alkaline processing compositions such as those described in US. Pat. 3,146,102.

In the present dye developer diffusion transfer system, the onium compounds are preferably utilized in the alkaline processing composition, although the onium compounds may also be utilized in the reception sheet, or less desirably, in one or more layers of the light-sensitive element, or in at least two of such positions.

The silver halide emulsions utilized in preparing photographic or light-sensitive elements used in the present diffusion transfer system may be any of the conventional negative-type, developing-out emulsions. Typical suitable silver halides include silver chloride, silver bromide, silver bromoiodide, silver chloroiodide, silver chlorobromoiodide and the like. Mixtures of more than one of such silver halides can also be utilized. In accordance with,

usual practice, such silver halide emulsions can contain spectral sensitizers, speed-increasing addenda, hardeners, coating aids, plasticizers, antifoggants and the like conventional emulsion addenda.

:In preparing such silver halide emulsions, as well as in preparing the various layers of photographic elements used in the present diffusion transfer process, including the layer containing the dye developer and colorless hydroquinone derivatives, mordant-containing reception layers, interlayers, topcoat layers and the like, a wide variety of hydrophilic organic colloids may be utilized as the vehicle or carrier. Gelatin is preferably used as the hydrophilic colloid or carrier material although such material as polyvinyl alcohol and its water-soluble derivatives and copolymers, Water-soluble copolymers such as \polyacrylamide, immidized polyacrylamide, etc., and other water-soluble film-forming materials that form Waterpermeable coats such as colloidal albumin, Water-soluble cellulose derivatives, etc., may be utilized in preparing the photographic elements. Compatible mixtures of two or more of such colloids may also be utilized.

The various layers utilized in preparing the diffusion transfer photographic elements of the invention may be coated on a wide variety of photographic supports. Typical supports include cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethylene terephthalate film, polyethylene film, polypropylene film, paper, polyethylene-coated paper, polypropylenecoated paper, glass and the like.

Similarly, a wide variety of receiving sheets may be utilized to receive the transfer images from the photographic elements. Typical reception layers for receiving sheets include such materials as linear polyamides, proteins such as gelatin, polyvinyl pyrrolidones, poly-4-vinyl pyridine, polyvinyl alcohol, polyvinyl salicylal, partially hydrolyzed polyvinyl acetate, methyl cellulose, regenerated cellulose, or mixtures of such. These reception layers may be coated on a suitable support of the type described above for the light-sensitive elements of the invention and including transparent as well as opaque supports.

Receiving sheets that release acidic material such as that derived from an acidic polymer or other acidic compound at a controlled rate as are described in US. Pat. 2,584,030 can be utilized to form positive transfer images. Such acidic materials are typically positioned in layers on the receiving sheet below the dye developer reception layer, there suitably being a spacer layer between the acid layer and the mordanting layer to control the release of acidic material. The acidic materials serve to neutralize residual portions of the alkaline activator on the receiving sheet.

A Wide variety of nonditfusible cationic or basic dyemordanting compounds can be used in liquid permeable reception layers including amines such as polymeric amines, quaternary ammonium compounds, quaternary phosphonium compounds and tertiary sulfonium compounds. Such mordants are non-ditfusible in the alkaline processing composition and contain at least one hydrophobic ballast group. As described above, either or both of the onium compounds and colorless hydroquinones can be incorporated on the receiving sheets. The receiving sheets can also contain development arrestors such as mercaptoazoles and iodides.

Light-sensitive elements containing integral reception layers for dye developer images may also be utilized. Such integral reception layers may be coated beneath the emulsion and dye developer layer near the support. A stripping layer coated over the integral reception layer may be used to facilitate the removal of the over-coated layers after the diffusion of the dye developer image to the reception layer.

The following nonlimiting examples are intended to illustrate the use of the azoniaanthracene dye developers in a photosensitive element and are given for illustrative purposes only.

6 EXAMPLE 1 A photosensitive element is prepared by coating suc cessively the following layers on a cellulose acetate film support:

(1) Dihydroxyazoniaanthracene dye developer layer An aqueous gelatin solution containing the dye developer, 5,8-dihydroxy-4a-azoniaanthracene bromide, is dis solved in a mixture of N-n-butyl-acetanilide, 4-methy1 cyclohexanone and the dispersing agent Alkanol B, and is passed through a colloid mill several times. Next, the mixture is coated on the film support at a coverage of 50 milligrams per square foot of the dye developer and milligrams of the gelatin per square foot. The coating is then dried so as to volatilize the 4-methyl cyclohexanone.

(2) Photosensitive emulsion layer A gelatino-silver bromide emulsion comprising 2.8 mole percent iodide is coated upon the dye developer layer in amounts sufficient to yield a coverage of 292 milligrams of silver per square foot and 200 milligrams of gelatin per square foot.

(3) Overcoat layer A gelatin coating is then spread over the photosensitive silver halide emulsion layer at a coverage of 256 milligrams per square foot. A sample of the freshly coated film is placed on a vacuum plate and is air dried in a vertical position, exposed imagewise on a density scale sensitomer and is processed with an aqueous alkaline solution of sodium metaborate octahydrate. The exposed film is processed with the alkaline solution for a period of five seconds, squeegeed and then rolled in contact with a color receiving sheet. The receiver comprises a paper support coated with a polyethylene layer carrying a gelatin layer containing a mixture of cationic mordant compounds of the type described in Bush US. Pat. 3,271,147. The exposed film and receiving sheet are maintained in contact for a period of 60 seconds. The negative is then separated from the receiving sheet and a light brown positive transferred image is obtained.

EXAMPLE 2 The procedure of Example 1 is repeated except that the exposed negative is processed in an activator solution comprising 45 grams per liter of sodium metaborate octahydrate and 45 grams per liter of sodium sulfite. The addition of the sodium sulfite to the processing solution results in a blue negative image being transferred to the receiving sheet.

EXAMPLE 3 The procedure of Example 2 is repeated with the exception that the processing solution additionally contains 13.5 grams per liter of auxiliary developer, ascorbic acid. As in Example 2, a blue negative transfer image is obtained. However, the addition of the ascorbic acid auxiliary developing agent results in a lower D Therefore, a color print having less background density and a better quality is obtained.

EXAMPLE 4 The procedure of Example 1 is repeated except that the gelatin overcoat of the photosensitive element additionally contains 20 milligrams per square foot of 4- methylphenyl hydroquinone, an auxiliary developing agent. The photosensitive element is then processed with an activator solution containing 45 grams per liter of sodium metaborate octahydrate and 45 grams per liter of sodium sulfite. A blue negative transfer print is obtained and the inclusion of the auxiliary developer in the gelatin overcoat results in a print having less background density than the negative print obtained in Example 2.

The following example illustrates the employment of a catechol azoniaanthracene dye developer in a diffusion transfer system.

EXAMPLE A photosensitive element is produced by successively coating the layers described in Example 1 on a cellulose acetate film support in a manner identical to that described. However, the catechol derivative dye developer, 5,6-dihydroxy-4a-azoniaanthracene bromide is substituted for the 5,8-dihydroxy-4a-azoniaanthracene bromide previously employed. The resulting photosensitive element is exposed and processed as previously described, and the receiving element is stripped from the photosensitive element. A brown positive image is obtained on the receiver. As may be seen from the foregoing examples, the dihydroxyazoniaanthracene salts of the present invention provide novel dye developing agents which may be employed to obtain positive and negative color transfer images.

The invention has been described in detail with particular reference to the preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope and spirit of the inveno R AN i on and

es 110 AN wherein R is selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group.

3. The photographic element of claim 2 wherein the r dye developer is a salt having a cation represented by the formula wherein R is selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group.

4. The photographic element of claim 3 wherein the dye developer is a salt of 5,8-dihydroxy-4a-azoniaanthracene.

5. A photographic product composed of a photosensitive element, an image rec iving layer and a rupturable container holding an aqueous alkaline processing solution, said photosensitive element being adapted so as to be capable of being superposed on the image-receiving layer and said rupturable container being adapted so as to be capable, upon being ruptured, of releasing said processing solution for application to said superposed photosensitive element and reception layer, said photosensitive element comprising a light-sensitive silver halide emulsion layer and, contiguous to the silver halide of said layer, a dye developer comprising a salt of a dihydroxyazoniaanthracene.

6. The photographic product of claim 5 wherein the dye developer is a salt having a cation selected from the group consisting of nt A1? l 7 I on and I e AN wherein R is selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group.

7. The photographtic product of claim 5 wherein the dye developer is a salt having a cation represented by the formula I e A/ 3 OH wherein R is selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group.

8. The photographic product of claim 5 wherein the dye developer is a salt of 5,8-dihydroxy-4a-azoniaanthracene.

9. The photographic product of claim 5 wherein the rupturable pod contains a solution comprising sodium sulfite.

10. In a process of forming a photographic image in color, the steps which comprise processing an exposed photographic element comprising a support, a light sensitive silver halide emulsion layer and a dye developer contiguous to the silver halide of said silver halide emulsion layer, said processing being effected by treating said photographic element with an alkaline liquid and thereby transferring said dye developer to a dye developer reception layer, said dye developer comprising a salt of a dihydroxyazoniaanthracene.

11. The process of claim 10 wherein the dye developer is a salt having a cation selected from the group consisting of wherein R is selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group.

l 69 R A N l OH wherein R is selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group.

13. The process of claim 12 wherein the dye developer is a salt of 5,8-dihydroxy-4a-azoniaanthracene.

14. The process of claim 13 wherein the dye developer 15 16. The process of claim 15 wherein the photographic element is processedin the presence of 4'-methylphenylhydroquinone.

17. The process of claim 15 wherein the photographic element is processed in the presence of ascorbic acid.

References Cited UNITED STATES PATENTS 3,375,253 Fields et a1. 260286 NORMAN G. TORCHIN, Primary Examiner A. T. -SURO PICO, Assistant Examiner US. Cl. X.R. 9676; 260-286 

